There are 11 kinds of Chenopodiaceae haloxylon plants in the world. They are mainly distributed in extensive desert areas from the Mediterranean to Central Asia and grow in moving sand dune, semi-fixed dune, salty soil and gravel gobi. China has Haloxylon ammodendorn (C.A.Me.) Bunge which is also called Haloxylon ammodendorn and Haloxylon apphyllum (Minkw), and Haloxylon persicum Bunge ex Boiss et Bushse. Haloxylon ammodendorn (C.A.Me.) Bunge is super xerophytic dungarunga and high arbuscular. The plant height is generally 2 to 3 m and individual plant can be 10 m high. The crown is generally dense and of semi spherical or approximate oval. Haloxylon ammodendorn (C.A.Me.) Bunge community with high canopy density in the desert looks like the forest landscape. Therefore, people usually call densely distributed haloxylon plants as “Haloxylon ammodendorn (C.A.Me.) Bunge Forest” previously. The distribution area of haloxylon plant is about 1170×104 hm2, accounting for 9% in China's total area of deserts. It is mainly distributed in deserts areas such as Xinjiang, Inner Mongolia, Qinghai, Gansu, Ningxia, etc. in Northwest China. However, Haloxylon persicum Bunge ex Boiss et Bushse is only distributed in the north of Xinjiang. Haloxylon ammodendorn (C.A.Me.) Bunge with the strongest stress resistance is a strong xerophytic-halphilous plant. Its ecological amplitude is wide and characterized by drought resistance, high temperature resistance, salt and alkali resistance and wind erosion resistance, it is a kind of plant with excellent wind prevention, sand fixation and ecological protection. In addition, Haloxylon ammodendorn (C.A.Me.) Bunge with solid wood and strong firepower is excellent firewood. It is reputed as “live coal in the desert”; its annual shoot is rich in nutrition and is excellent livestock feed; in addition, it is also the host of cistanche deserticola-“desert ginseng” which has high economic and development value. Haloxylon ammodendorn (C.A.Me.) Bunge is precious plant resource in desert and semi-desert areas in Northwest China and also tree species with maximum dune-fixation forestation area in arid desert areas in China. It has irreplaceable economic position and important utility value in sand prevention and stabilization, mitigating desertification and maintaining ecological safety. However, due to human factors and environmental degradation, resources of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse are destroyed so seriously that they have become vulnerable and listed as national endangered three-level protection plants. Hence, it is an important project of northwest ecological construction to accelerate restoration and construction of haloxylon plant forest.
However, there are many difficulties during natural restoration and rapid construction of haloxylon plant forest. A critical problem is that the survival rate of a directly-planted seedling and a transplanting seedling of a haloxylon plant is extremely low. A lot of field surveys indicate that the survival rate of natural sprouting in native place of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse and manually-planted seedling is only about 1%. And the survival rate of manually transplanted annotinous and biennial Haloxylon ammodendorn (C.A.Me.) Bunge sapling is only about 10%. Namely, many seedlings sprouting in spring, manually-planted seedlings, and transplanted seedlings die from spring to autumn. It was held that the main reason was extreme degradation of desert environment of native range of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse. High temperature and drought cause the seedling and sapling to die. In addition, some seedlings are buried by wind-sand and gnawed by animals. However, findings of surveys and researches of the project group in Gurbantunggut Desert area in Junggar Basin for many years indicate that desert environment of native range of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse are not seriously short of water. Even sandy soil layer below 60 cm is filled with abundant suspension moisture from the arid middle ten days of June to the last ten days of August. Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse generally sprout or bud from the middle ten days of March to the last ten days of April. As there are many snows and rains in spring, shallow sand is filled with water. The root of a seedling or sapling grows rapidly and the root length can exceed 60 cm at the middle ten days of June; as the sandy soil layer below 60 cm is still filled with suspension moisture after the middle ten days of June, growth demand of seedling can be satisfied basically. Thus, drought is not the important reason that causes death to haloxylon plant seedling. High temperature (air temperature) is not the main reason causing death to a lot of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse seedlings. The experimental research indicates that a seedling and sapling can grow normally under 50° C. high temperature environment of several successive days with certain moisture. In addition, burying of wind-sand and animal gnawing do cause death to seedling. But it is not the main reason causing a lot of deaths. Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse have strong sand burying resistance and regeneration capacity.
Findings of surveys and researches for many years indicate that high temperature (≧50° C., average temperature) of ground surface layer (0 to 2 cm) in desert and semi-desert areas is critical and the important reason causing death to a lot of deaths of seedlings of haloxylon plants. The ecological environment in the desert and semi-desert hinterland in Northwest China is extremely bad in summer. The temperature of the ground surface layer can reach above 60° C. and extreme temperature of the ground surface layer can reach about 80° C. For instance, as for Gurbantunggut Desert hinterland in Junggar Basin of Xinjiang, June to August is dry and of little rain in summer. The temperature is high and the temperature of the ground surface layer is higher. The air temperature at daytime often exceeds 40° C. and the temperature of the ground surface layer can reach about 75° C. High temperature of the ground surface layer often poses serious damage stress to plants. The reaction part of threat lies in the connection between the base part of the stem of plant and the ground surface. Plants undergo significant physiological reaction due to the threat of high temperature stress. Plant with light reaction grows slowly or stagnates at the overground part and the underground part. Plants with serious reaction directly cause the whole plant to die. Desert plants such as Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse have strong stress resistance. However, the seedling and sapling cannot endure high temperature stress of the ground surface layer above 60° C. for a long time. It is just the reason that causes the low survival rate of natural seedling, directly planted seedling and transplanted seeding of haloxylon plants in Gurbantunggut Desert hinterland of Xinjiang. It not only causes community dominated by haloxylon plants to be hard to recover after damage, but also poses difficulty to afforestation. In addition, the high temperature of ground surface layer causes seedling (below 5 years old), sampling (5-10 years old) and bearing tree (above 10 years old) of haloxylon plants to “be summer dormant”. The growth is caused to be slowed down or stagnated. Thus, the annual valid growing period is shortened and annual increment is reduced. A precedent can fully interpret that the high temperature of ground surface layer is the critical factor causing death to a seedling and sapling of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse. Only a few years ago, a certain forestry bureau in Altay Prefecture, Xinjiang planted and transplanted Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse of 3000 Mu around the management and protection station of public welfare forest in administered Karamori Mountain Nature Reserve. The area is a typical ecological environment of Gurbantunggut Desert hinterland. To improve the survival rate of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse, they adopted measures such as irrigating root, grass grid sand prevention, etc. Instead of protecting sapling of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse from high temperature stress of the ground surface layer. The 3000 Mu saplings of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse died after two years. Above instances show that if we are to restore and build an ecological forest of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse on a large scale in desert or semi-desert environment in Northwest China, the critical issue that seedling and sapling of Haloxylon ammodendorn (C.A.Me.) Bunge and Haloxylon persicum Bunge ex Boiss et Bushse are protected from high temperature stress of ground surface layer shall be overcome.
In light of the reason, the applicant provides a method to protect haloxylon plants with protective screening at the time of applying for CN101965788A of patent for invention in China to improve the survival rate of a seedling. However, the method of adopting protective screening has the following defects in desert and semi-desert areas with strong wind-sand: {circle around (1)}The sunshade net is easy to be damaged and the sand in the base part is easy to be blew away to expose a gap and anchorage claw, which influences the effect of preventing gnawing of small animals, moisturizing, preventing damage and burying of wind-sand and reducing temperature of the ground surface layer. {circle around (2)}The sunshade net has holes and the moisturizing effect is relatively weak. {circle around (3)}The sunshade net is easy to be damaged and the sand in the base part is easy to be blown away. As a result, the maintenance cost is relatively high each year. {circle around (4)}The production cost of protective screening is relatively high. The production price of each one is RMB 5.00-6.00. Furthermore, it should be produced manually, wasting time and energy.